only use siginterrupt() if it really exists on the platform
diff --git a/tests/server/sws.c b/tests/server/sws.c
index 8ee2e96..b006c2b 100644
--- a/tests/server/sws.c
+++ b/tests/server/sws.c
@@ -537,6 +537,8 @@
 
 #ifdef HAVE_SIGNAL
   signal(SIGPIPE, sigpipe_handler);
+#endif
+#ifdef HAVE_SIGINTERRUPT
   siginterrupt(SIGPIPE, 1);
 #endif